1. Field of the Invention
The present invention relates to recording/reproducing, and more particularly, to a method and apparatus for generating/detecting a stable and exact tracking error signal.
2. Discussion of the Related Art
With the increase of recording capacity, recording media that can record large-scaled data, such as CD, DVD, and a high-density recording medium (for example, HD-DVD and BD), have been continuously developed, wherein the high-density recording medium recently developed can record and store video data of high picture quality and audio data of high sound quality for a long time. Also, these recording media are being developed as recording media that are more convenient and useful, in accordance with improvement of recording/reproducing speed as well as the increase of recording capacity.
Generally, the recording medium is divided into a lead-in area, a data area, and a lead-out area. These areas may be used as other terminologies in accordance with types and use of the receiving medium, and may additionally be provided with a specific area such as additional information or test area. However, most of the recording media have the aforementioned three areas.
Furthermore, a track is formed in a recording layer of the recording medium. Since data are recorded along the track, it is necessarily required for a pickup of a recording/reproducing apparatus to exactly trace the track to record or reproduce the data. To this end, the recording/reproducing apparatus detects a tracking error signal and controls the position of the pickup based on the tracking error signal. Generally, the conventional recording/reproducing apparatus obtains the tracking error signal using one main beam and two sub beams. In this case, the two sub beams are to compensate an error generated by motion of the main beam, wherein the motion of the main beam is caused by motion of the pickup. The two sub beams are generated by a diffractive device located in front of a light source. Namely, as the main beam is diffracted by the diffractive device, the two sub beams are generated. After the main beam and the two sub beams are reflected by the recording medium, they are detected by a light-receiving device of the recording/reproducing apparatus.
However, it is difficult to generate/detect stable and exact sub beams due to an inner error (aberration) of the recording/reproducing apparatus in generating/detecting the two sub beams. Accordingly, the positions of the diffractive device and the light-receiving device should be adjusted to stably and exactly generate/detect the sub beams. However, since the beams formed in the light-receiving device are very small and the position of the light-receiving device is performed in conjunction with the position of the diffractive device, control in the position of the light-device device is not easy and its exactness is not high. Accordingly, there is limitation in obtaining the exact tracking error signal.